First, I'd like you to realize that there are many definitions of "knowing" a language. Does it mean being able to have a conversation? Being able to watch the news and understand? Being able to read a book? How about the newspaper?
Depending on the definition I "know" 4 languages, use many more and am fluent in just 1 <-- that would be English!
In our home we have 4 common languages, 3 which get us through the day. These three are the ones the kids have the best handle on. In addition to those languages we have a few others which the kids come into contact with regularly. Do they get confused... no. Do they intentionally mix languages... yes. Do I get confused - sometimes!
Here are some of the things we do to expose our kids to various languages (including ones we can't read/write/speak!) in a way that is natural and picks their curiosity:
- Have books from the same series in various languages. Sometimes I'll get the same book, other times I'll get similar books, one in each language.
Example: Thomas and Friends, きかんしゃトーマス、Thomas und seine Freunde
- Bilingual books are great too!
- If you are not sure of pronounciation then a book with accompanying CD can help.
- Multilingual TV shows are another way to bring in a language. Zilla's interest in Spanish comes mainly from shows like Handy Manny, Dora and Diego.
I love to use music to learn languages... or perhaps it is more accurate to say that I enjoy music which happens to include various languages.
- The Wiggles, while mainly in English, include songs from various languages and cultures.
- Listening to songs like some of those in Riding the Wind which include 2 or more languages ( I can't read French but I can sing along!)
- Taize - a great community which has multilingual podcasts for free. It is great music/readings for relaxing and meditation or to set the mood for a peaceful dinner with preschoolers!
Perhaps the most fun way for me is picking up children's picture books in various languages when we go on vacation or receiving them as souvineers when someone returns from their travels.
Another fairly easy way to bring in languages yet help them to connect in children's minds is to have Bible stories where you can read the corresponding stories in various languages.
You can do all of these things and more to encourage language learning but no matter how well you prepare the environment the key component is to actually use the language, not just repeat a set of sounds. Interacting, playing, conversing together is key. You don't need to be fluent or have perfect pronouciation because successfully using a language isn't about how much you know, it is about how you use what you know.